package com.budbreak.pan.controller.config.filter;


import com.budbreak.pan.entity.pan.User;
import com.budbreak.pan.service.WebUtil;
import com.budbreak.pan.service.pan.shiro.JWTToken;
import com.budbreak.pan.service.pan.shiro.JwtUtils;
import org.apache.commons.lang3.BooleanUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpStatus;
import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.filter.authc.AuthenticatingFilter;
import org.apache.shiro.web.util.WebUtils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.stream.Collectors;

public class JwtAuthFilter extends AuthenticatingFilter {
    private final Logger log = LoggerFactory.getLogger(JwtAuthFilter.class);

    private static final int tokenRefreshInterval = 300;

    public JwtAuthFilter(){
        this.setLoginUrl("/api/v1/pan/user/login");
    }

    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = WebUtils.toHttp(request);
        //对于OPTION请求做拦截，不做token校验
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            return false;
        }

        //TODO 是否考虑在此做用户认证(以省去JwtRealm),下方调用super.preHandle()会调用isAccessAllowed()方法执行subject.login()进行realm验证
        return super.preHandle(request, response);
    }


    @Override
    protected void postHandle(ServletRequest request, ServletResponse response){
        this.fillCorsHeader(WebUtils.toHttp(request), WebUtils.toHttp(response));
        request.setAttribute("jwtShiroFilter.FILTERED", true);
    }

    /**
     * 父类会在请求进入拦截器后调用该方法，返回true则继续，返回false则会调用onAccessDenied()。这里在不通过时，还调用了isPermissive()方法，我们后面解释。
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        HttpServletResponse httpServletResponse = WebUtils.toHttp(response);
        HttpServletRequest httpServletRequest = WebUtils.toHttp(request);
        if(this.isLoginRequest(request, response)) {
            return true;
        }
        Boolean afterFiltered = (Boolean)(request.getAttribute("jwtShiroFilter.FILTERED"));
        if( BooleanUtils.isTrue(afterFiltered)) {
            return true;
        }
        Cookie[] cookies = httpServletRequest.getCookies();
        String token = null;
        if (cookies != null) {
            List<Cookie> collect = Arrays.stream(cookies).filter(cookie -> cookie.getName().equals("x-auth-token")).collect(Collectors.toList());
            if (collect.size() > 0) {
                token = collect.get(0).getValue();
            }
        }
        if (null != token && null != JwtUtils.getUsername(token)) {
            return true;
        }else {
            try {
                httpServletResponse.sendRedirect("/");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        boolean allowed = false;
        try {
            // 在header取得的token用于后续jwtRealm验证
            allowed = executeLogin(request, response);
        } catch(IllegalStateException e){ //not found any token
            log.error("Not found any token");
        }catch (Exception e) {
            log.error("Error occurs when login", e);
        }
        return allowed || super.isPermissive(mappedValue);
    }
    /**
     * 这里重写了父类的方法，使用我们自己定义的Token类，提交给shiro。这个方法返回null的话会直接抛出异常，进入isAccessAllowed（）的异常处理逻辑。
     */
    @Override
    protected AuthenticationToken createToken(ServletRequest servletRequest, ServletResponse servletResponse) {
        String jwtToken = getAuthzHeader(servletRequest);
        if(StringUtils.isNotBlank(jwtToken)&&!JwtUtils.isTokenExpired(jwtToken)) {
            return new JWTToken(jwtToken);
        }

        return null;
    }
    /**
     * 如果这个Filter在之前isAccessAllowed（）方法中返回false,则会进入这个方法。我们这里直接返回错误的response
     */
    @Override
    protected boolean onAccessDenied(ServletRequest servletRequest, ServletResponse servletResponse) throws Exception {
        HttpServletResponse httpResponse = WebUtils.toHttp(servletResponse);
        httpResponse.setCharacterEncoding("UTF-8");
        httpResponse.setContentType("application/json;charset=UTF-8");
        httpResponse.setStatus(HttpStatus.SC_NON_AUTHORITATIVE_INFORMATION);
        fillCorsHeader(WebUtils.toHttp(servletRequest), httpResponse);
        return false;
    }
    /**
     *  如果Shiro Login认证成功，会进入该方法，等同于用户名密码登录成功，我们这里还判断了是否要刷新Token
     */
    @Override
    protected boolean onLoginSuccess(AuthenticationToken token, Subject subject, ServletRequest request, ServletResponse response) throws Exception {
        HttpServletResponse httpResponse = WebUtils.toHttp(response);
        String newToken = null;
        if(token instanceof JWTToken){
            JWTToken jwtToken = (JWTToken)token;
            User user = (User) subject.getPrincipal();
            boolean shouldRefresh = shouldTokenRefresh(JwtUtils.getIssuedAt(jwtToken.getToken()));
            if(shouldRefresh) {
                newToken = JwtUtils.sign(user.getUsername(), user.getAlias(), 3600);
            }
        }
        if(StringUtils.isNotBlank(newToken)) {
            httpResponse.setHeader("x-auth-token", newToken);
        }

        return true;
    }
    /**
     * 如果调用shiro的login认证失败，会回调这个方法，这里我们什么都不做，因为逻辑放到了onAccessDenied（）中。
     */
    @Override
    protected boolean onLoginFailure(AuthenticationToken token, AuthenticationException e, ServletRequest request, ServletResponse response) {
        log.error("Validate token fail, token:{}, error:{}", token.toString(), e.getMessage());
        return false;
    }

    protected String getAuthzHeader(ServletRequest request) {
        HttpServletRequest httpRequest = WebUtils.toHttp(request);
        String header = httpRequest.getHeader("x-auth-token");
        return StringUtils.removeStart(header, "Bearer ");
    }

    protected boolean shouldTokenRefresh(Date issueAt){
        LocalDateTime issueTime = LocalDateTime.ofInstant(issueAt.toInstant(), ZoneId.systemDefault());
        return LocalDateTime.now().minusSeconds(tokenRefreshInterval).isAfter(issueTime);
    }

    protected void fillCorsHeader(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse){
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,HEAD");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
    }
}
